My guess is that you have identified the problem.
The flourescent lights actually turn on and off 30 times per second. If you are shooting at 60 i or 30p, and you are not perfectly synced with them, you will get a banding of brighter or darker moving up the screen.
I find that with 60i it is less pronounced but still there. I find different flourescents have a more or less effect. Maybe the age of the bulbs is newer or older than the rest. Or maybe you had some window light coming in to hide the problem in some shots comapare to the others.
I have found mercury vapor even worse. The kind in hockey stadiums and gyms.
What I have done to minimize the effect going into the place is to try different shutter speeds to find the minimum effect, often I use 1/150 shutter speed.
I have not, however found a way to fix it in post.
John
John Lenihan
LeniCam Video Productions
https://www.lenicamvideoproductions.com